Dense Phase PSV Calcs 1

[MatthewD]

I can't seem to find the appropiate calculations for PSV relief flowrate calculations for natural gas in the dense phase. Am I just missing something? or does anyone know of some resources that may be of help

 

[Guidoo]

Use following link to article in Chemical Engineering Progress:

http://www.cepmagazine.org/pdf/080234.pdf

 

[MatthewD]

Thats gold....thanks

 

[Guidoo]

Check out the correction as well:

http://www.cepmagazine.org/pdf/100208.pdf

 

[MatthewD]

But are we sure supercritical is equivelent to dense phase...I have a very poor thermodynamic background

 

[25362]

To MatthewD, a critical state is defined as the condition of pressure, temperature and composition at which all properties of coexisting liquid and vapor are identical. I.e., there is no distinction between liquid and vapor.

In this sense a dense natural gas -whose conditions are outside the P,T envelope in a isoplethic diagram- could be considered supercritical, since warming would bring about a gradual change in density without the appearance of a new phase.

Dense phase natural gas (aka DPNG) at pressures higher than the cricondenbar may partially condense on depressurizing (a process called "retrograde" condensation) at constant temperature, in particular when this temperature is lower than the cricondentherm. It can return to fully vaporized gas upon a further reduction in presure or by heating, so as to reach again the dew point line. Don't forget natural gas is a mixture, not a pure -single component- gas.

One site I found on the web that may interest you:

http://www.synetix.com/technical/pdfs/papers/gpavenezuela.pdf